PROJECT SUMMARY/ABSTRACT The prevalence of opioid use and related disorders has reached epidemic rates in United States. Medication-assisted treatment (MAT), the use of pharmacotherapy in combination with behavioral therapies, is associated with significant reductions in illicit opioid use. Buprenorphine, a partial opioid agonist, is one pharmacological option for MAT that is growing in popularity because of its more flexible administration through office-based programs. Despite its many advantages, nearly half of participants are unsuccessful in achieving buprenorphine stabilization. Distress tolerance (DT), defined as the perceived or actual ability to handle aversive physical or emotional states, is a transdiagnostic vulnerability factor implicated in the development and maintenance of substance use. Targeting DT during substance use treatment may improve outcomes by promoting the ability to persist in goal directed activity (e.g., abstinence) even when experiencing physical or emotional distress. Personalized feedback interventions (PFI) represent a promising method to effectively motivate engagement in and adherence to buprenorphine treatment, particularly among individuals characterized by low DT. These interventions are generally brief, individually tailored, and have the potential to be delivered via mobile platforms (e.g., computers, text message). Dr. Langdon's career goal is to conduct patient-oriented research focused on the development and evaluation of novel digital health interventions to enhance engagement in and adherence to MAT. The integrated training and research plans proposed in this application will provide Dr. Langdon with advanced training in several critical areas needed to enhance her program of research toward this career goal. In collaboration with her mentors, training will be targeted to the following domains: 1) nature and treatment of opioid use disorders; 2) treatment development; 3) digital health interventions; 4) clinical trial methodology; and 5) professional development. These training objectives will be achieved through a combination of didactic and applied activities as well as the application of these skills in a Stage 1 behavioral treatment development trial. Target areas for learning are directly linked to the specific aims of this research study, which include (1) the development and refinement of an interactive computer- and text message-delivered PFI, that incorporates DT skills training, for persons actively seeking outpatient MAT (PFI- DT); (2) pilot testing the efficacy of PFI-DT for increasing motivation, abstinence, adherence, and retention to treatment compared to a health education comparison condition; and, (3) examination of potential mechanisms that may underlie the efficacy of the PFI-DT in improving outcomes, including distress tolerance, self- regulation, and negative affect. This K23 Award would provide Dr. Langdon with a range of advanced skills designed to complement her prior training so that she may successfully transition into an independent scientist focused on addressing the public health burden of opioid use disorders through the development of effective, easily-disseminated, technology-augmented interventions.